Form for concrete-pipe molds



J. C. MITCHELL. FORM FOR CONCRETE PIPE MOLDS'. APPLICATION FILED SEPT.'2 1920.

1,397,649; Patented Nov. 22, 1921.

JOHN C. MITCHELL, OF EAST ORANGE, NEW JERSEY.

FORM FOR CONCRETE-PIPE MOLDS.

Specification of Letters Patent.

application filed September 21, 1920. Serial No. 411,722.

To (time hem it may concern Be it known that I, JOHN C. MITCHELL, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Forms for Concrete-Pipe Molds, of which the following is a full, clear, and exact description.

In the manufacture of concrete plpes, either with or without reinforcement, it is customary to set up an outer and an inner mold or form, with an annular spacebetween, and to pack such space with concrete. After the latter has set and sufficiently hard ened the forms are removed. No difiiculty is experienced in removing the outer mold or form, as this may be made up of longitudinally hinged sections which may be readily unlocked and spread. To remove the inner form, is not, however, so simple a matter, for, while this also may be built in hinged sections, great nicety in forming the parts is demanded and great care must be exercised in looking them, and when they the unlocked or released they are not easily collapsed and removed.

In a companion application I have shown and described a new form of mold which, for its removal, requires only that certain members thereof be slightly raised, with the result that thereby, after it has been unlocked, it is reduced in circumference so that a further raising of the said members lifts it freely from the pipe.

The construction of this improved form, however, was devised and designed with the special object of making pipes of relatively great length. For shorter pipes, I have devised a more simple form which also has the capability of being reduced in circumference to separate it from the finished pipe and to enable it to be lifted out of said pipe, and this simplified form is the subject of my present application for Letters Patent.

According to my present invention, I employ a form composed preferably, although not necessarily, of sheet metal and split it along one line. To one edge of this split cylinder I hinge a plate of peculiar shape or character to form a section of the complete cylinder, which is connected with the adjacent edge portion of the cylinder by a device in the nature of a toggle. When this form is closed or set up ready for use the hinged section is turned to complete the cylindrical surface, and by such movement the toggle is straightened so asto hold the section firmly in place, but after the mold. is packed and the concrete forming the pipe has hardened or set. the toggle is knocked down, releasing the hinged section,which is then turned inward withthe result that the two adjacent edges of the form will come together or. may be readily forced together so as to reduce, correspondingly, the circumference of the form and thus render it easy to lift it out from the surrounding wall of concrete. I

This improved form I have illustrated in the accompanying drawing, in which- Figure 1 shows the novel portion of the mold closed or in condition for use, and

Fig. 2 the same part, but opened to permit of the edges coming together;

These molds are familiar. in a general way to all skilled in the art. I have, therefore, shown only the essential features of the inner form, it being understood that the outer form may be of any desired or known kind and construction.

The form proper is composed of a sheet metal or similar cylinder 1, split longitudinally from end to end. Toione edge of this split cylinder is secured an ordinary hinge 2, to the free leaf of which is secured a plate 3 of the shape of an arc of the complete cylinder and having projecting radially inward from it a plate or bar 41. To this bar is secured an angle iron 5 which is connected by an ordinary form of toggle 6 to the inner surface of the other or adjacent edge of the cylinder 1.

The bar or plate 4 serves or may be fashioned specially to constitute a handle, and when the form is set up this is turned, as shown in Fig. 1, to close the cylinder by the section plate 3. When in this position the toggle is locked and no pressure upon the outside of the section 3 will displace it. After the pipe has been formed and has set or hardened the toggle may be knocked down by a hammer or released by the handle, which is then turned to the position shown in Fig. 2, in which the edges of the cylinder, as will be seen, can come together, which results in a reduction of the circumference of the cylinder from which it follows that it is freed all around from the surrounding walls of concrete. Having been thus freed, the form may readily be lifted out of the plpe.

llatenfted Nov. 22, 1921.

As I have explained above, this device is more particularly useful inmaking pipes of small or moderate sizes or lengths, in which the forms of the mold are not too cumbersome to be placed and removed by hand and 7 Without the use of'cranes and other; 31.491334? ratus of thatnatuie. It is infinitely more practical and efiicient than the ordinary,

collapsible molds because oi the extremely simple nature oi its use and operation. It requires no speclal care in 1ts successful use; it is not subject to deterioration nor one edge of the same,"a bar or plate extending inwardly from such plate anda toggle connecting the said bar to a point near the adjacent edge of the cylinder.

-.2." An inner form for a concrete pipe mold, comprising in combination, a longitudinally split cylinder of sheet metal, a narrowsection forming a portion of and completing the full cylinder by being hinged to one edge oi the cylindrical sheet a toggle com-.

prised of the said narrow sectlon'having a radial arm as one llnk and a hlnged member connecting the radial arm of the nar signature.

JOHN C. MITCHELL 

